Wind farm noise causes “clear and significant” damage to people’s sleep and mental health, according to the first full peer-reviewed scientific study of the problem.

American and British researchers compared two groups of residents in the US state of Maine. One group lived within a mile of a wind farm and the second group did not.

Both sets of people were demographically and socially similar, but the researchers found major differences in the quality of sleep the two groups enjoyed.

The findings provide the clearest evidence yet to support long-standing complaints from people living near turbines that the sound from their rotating blades disrupts sleep patterns and causes stress-related conditions.

The study will be used by critics of wind power to argue against new turbines being built near homes and for existing ones to be switched off or have their speed reduced, when strong winds cause their noise to increase.

The researchers used two standard scientific scales, the Pittsburgh Sleep Quality Index, which measures the quality of night-time sleep, and the Epworth Sleepiness Scale, which measures how sleepy people feel when they are awake.

More than a quarter of participants in the group living near the turbines said they had been medically diagnosed with depression or anxiety since the wind farm started. None of the participants in the group further away reported such problems.

Each person was also asked if they had been prescribed sleeping pills. More than a quarter of those living near the wind farm said they had. Less than a tenth of those living further away had been prescribed sleeping pills.

According to the researchers, the study, in the journal Noise and Health, is the first to show clear relationships between wind farms and “important clinical indicators of health, including sleep quality, daytime sleepiness and mental health”.

Unlike some common forms of sleep-disturbing noise, such as roads, wind turbine noise varies dramatically, depending on the wind direction and speed. Unlike other forms of variable noise, however, such as railways and aircraft, it can continue for very long

periods at a time. The nature of the noise – a rhythmic beating or swooshing of the blades – is also disturbing. UK planning guidance allows a night-time noise level from wind farms of 42 decibels – equivalent to the hum made by a fridge.

This means that turbines cannot be built less than 380-550 yards from human habitation, with the exact distance depending on the terrain and the size of the turbines.

However, as local concern about wind farm noise grows, many councils are now drawing up far wider cordons. Wiltshire, for instance, has recently voted to adopt minimum distances of between 0.6 to 1.8 miles, depending on the size of the turbines.

Dr Lee Moroney, director of planning at the Renewable Energy Foundation, said: “The UK noise limits were drawn up 16 years ago, when wind turbines were less than half the current size. Worse still, the guidelines permit turbines to be built so close to houses that wind turbine noise will not infrequently be clearly audible indoors at night time, so sleep impacts and associated health effects are almost inevitable.

“This situation is obviously unacceptable and creating a lot of angry neighbours, but the industry and government response is slow and very reluctant. Ministers need to light a fire under their civil servants.”

The research will add to the growing pressure on the wind farm industry, which was attacked last week by the junior energy minister, John Hayes, for the way in which turbines have been “peppered around the country without due regard for the interests of the local community or their wishes”. Saying “enough is enough”, Mr Hayes appeared to support a moratorium on new developments beyond those already in the pipeline.

He was slapped down by his Lib Dem boss, Ed Davey, the Energy Secretary, but is unlikely to have made his remarks without some kind of nod from the top of Government. George Osborne, the Chancellor, is known to be increasingly sceptical about the effectiveness of wind power, which is heavily subsidised but delivers relatively little reduction in carbon dioxide.

Wind farms generate about a quarter of their theoretical capacity because the wind does not always blow at the required speeds. Earlier this year, more than 100 Tory MPs urged David Cameron to block the further expansion of wind power.

Whatever the Government decides, however, may not matter.

The Sunday Telegraph has learnt that the EU will shortly begin work on a new directive which may impose a binding target for further renewable energy, mostly wind, on the UK. There is already a target, which is also Government policy, that 20 per cent of energy should come from renewables by 2020.

But Brussels is considering imposing an even higher mandatory target to be met over the following decade, according to Gunther Oettinger, the EU energy commissioner. “I want an interesting discussion on binding targets for renewables by 2030,” he said earlier this year.

Two weeks ago, a senior member of his staff, Jasmin Battista, said that Mr Oettinger was “open to” forced targets, though no decision had been made.

The European Parliament has voted for mandatory increases in renewables by 2030 and Mr Davey has also said he favours them. The issue will be considered at a European Council of Ministers meeting next month.

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